Circuit => Add Variable

Circuit Menu - Add/Edit Variable Dialog Box

This dialog box is opened when you select the Circuit => Add Variable command in the project editor or click on the New or Edit button in the Variable List dialog box (Circuit => Variable List) and allows you to enter a new variable or edit an existing variable. Variables can be used to define the value of parameters in your circuit. This dialog box is also opened if you enter a presently undefined variable in another dialog box, such as the Dielectric Editor, the Metal Editor, or the Component Properties dialog box. Fields in which you may enter a variable instead of a constant, or nominal,  value are identified with a drop down list, an example of which is pictured below.  The list includes the entries <Add Variable> and <Edit Variable> in addition to any existing variables. Selecting <Add Variable> from the list opens this dialog box to allow you to create the variable. The <Edit Variable> entry only appears if you have entered an existing variable as the value for this field. Selecting this entry opens the Add/Edit variable dialog box to edit the presently entered variable.

Name: Enter the desired name for the variable here. If you are editing a pre-existing variable that is presently being used in your project, than this field is disabled. To change the name, you must first delete all occurrences of the variable in the project.

Value or Equation: This field defines the value of the variable. You may enter an actual value or an equation which defines the value. This equation may use other variables which are defined in your project. A list of the presently defined variables appears just to the left. For information about what functions are available and equation syntax, click on the Equation Syntax Help button to open online help.

Warning: Care must be taken to not create a circular dependency in which two variables each rely on the other variable to determine their value. This will result in an error message.

Description: You may enter a brief description here of the variable. This description appears in the Variable list dialog box and allows you to identify the purpose of the variable or which parameter it is being used to define. If the variable is created when editing a dialog box (Dielectric Layers, Metal Types, etc.) a default description is provided by the software. This may be changed by entering a different description here.

Units: You may select the units used for the variable from this drop list. If the variable is created when editing a dialog box (Dielectric Layers, Metal Types, etc.) a default unit is provided by the software. This may be changed by selecting a different unit here. If the desired unit does not appear in the list, select "Other."

When using a unit other than “Other”, the value will scale if you change your default units. For example if you set this unit to microns, then set your default for the project to mils, then the variable will be converted to the equivalent nominal value of mils.

Available Variables: This is a list of the variables that are presently defined in the project. If you wish to insert an existing variable in the definition of the variable you are adding or editing, select the desired variable in the list, then click on the Insert into Eqn button just below the list.